Microwave sintering of graphene-nanoplatelet-reinforced Al2O3-based composites

Abstract

In this study, we performed a microwave sintering (MWS) of Al2O3 ceramic and Al2O3-based composites with nominal contents of graphene nanoplatelets (GPLs) of 0.2, 0.4, 0.6, and 0.8 vol%. The GPL dispersion in N-methyl pyrroleketone was optimized to deagglomerate the GPLs without damaging their structure. Dense composites were then obtained by MWS at 1500°C for 30 min. The effects of different GPL contents on the phase compositions, microstructures, and mechanical properties of the composites were investigated. The microstructures of the composites became finer with the incorporation of the GPLs. The well-dispersed GPL fillers led to higher sintered densities in the composites. The optimal mechanical properties were achieved with 0.4 vol% GPLs. For this sample, the hardness, fracture toughness, and bending strength were 2000 kgf/mm2, 6.19 MPa•m1/2, and 365.10 MPa, respectively. The addition of GPL could improve the microstructure of the Al2O3 ceramic and has potential to improve the fracture toughness of the ceramics.